LLVM 17.0.0git
PhiValues.h
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1//===- PhiValues.h - Phi Value Analysis -------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the PhiValues class, and associated passes, which can be
10// used to find the underlying values of the phis in a function, i.e. the
11// non-phi values that can be found by traversing the phi graph.
12//
13// This information is computed lazily and cached. If new phis are added to the
14// function they are handled correctly, but if an existing phi has its operands
15// modified PhiValues has to be notified by calling invalidateValue.
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_ANALYSIS_PHIVALUES_H
20#define LLVM_ANALYSIS_PHIVALUES_H
21
22#include "llvm/ADT/DenseMap.h"
23#include "llvm/ADT/DenseSet.h"
24#include "llvm/ADT/SetVector.h"
25#include "llvm/IR/PassManager.h"
26#include "llvm/IR/ValueHandle.h"
27#include "llvm/Pass.h"
28
29namespace llvm {
30
31class Value;
32class PHINode;
33class Function;
34
35/// Class for calculating and caching the underlying values of phis in a
36/// function.
37///
38/// Initially the PhiValues is empty, and gets incrementally populated whenever
39/// it is queried.
40class PhiValues {
41public:
43
44 /// Construct an empty PhiValues.
45 PhiValues(const Function &F) : F(F) {}
46
47 /// Get the underlying values of a phi.
48 ///
49 /// This returns the cached value if PN has previously been processed,
50 /// otherwise it processes it first.
51 const ValueSet &getValuesForPhi(const PHINode *PN);
52
53 /// Notify PhiValues that the cached information using V is no longer valid
54 ///
55 /// Whenever a phi has its operands modified the cached values for that phi
56 /// (and the phis that use that phi) become invalid. A user of PhiValues has
57 /// to notify it of this by calling invalidateValue on either the operand or
58 /// the phi, which will then clear the relevant cached information.
59 void invalidateValue(const Value *V);
60
61 /// Free the memory used by this class.
62 void releaseMemory();
63
64 /// Print out the values currently in the cache.
65 void print(raw_ostream &OS) const;
66
67 /// Handle invalidation events in the new pass manager.
70
71private:
72 using ConstValueSet = SmallSetVector<const Value *, 4>;
73
74 /// The next depth number to be used by processPhi.
75 unsigned int NextDepthNumber = 1;
76
77 /// Depth numbers of phis. Phis with the same depth number are part of the
78 /// same strongly connected component.
80
81 /// Non-phi values reachable from each component.
82 DenseMap<unsigned int, ValueSet> NonPhiReachableMap;
83
84 /// All values reachable from each component.
86
87 /// A CallbackVH to notify PhiValues when a value is deleted or replaced, so
88 /// that the cached information for that value can be cleared to avoid
89 /// dangling pointers to invalid values.
90 class PhiValuesCallbackVH final : public CallbackVH {
91 PhiValues *PV;
92 void deleted() override;
93 void allUsesReplacedWith(Value *New) override;
94
95 public:
96 PhiValuesCallbackVH(Value *V, PhiValues *PV = nullptr)
97 : CallbackVH(V), PV(PV) {}
98 };
99
100 /// A set of callbacks to the values that processPhi has seen.
101 DenseSet<PhiValuesCallbackVH, DenseMapInfo<Value *>> TrackedValues;
102
103 /// The function that the PhiValues is for.
104 const Function &F;
105
106 /// Process a phi so that its entries in the depth and reachable maps are
107 /// fully populated.
108 void processPhi(const PHINode *PN, SmallVectorImpl<const PHINode *> &Stack);
109};
110
111/// The analysis pass which yields a PhiValues
112///
113/// The analysis does nothing by itself, and just returns an empty PhiValues
114/// which will get filled in as it's used.
115class PhiValuesAnalysis : public AnalysisInfoMixin<PhiValuesAnalysis> {
117 static AnalysisKey Key;
118
119public:
122};
123
124/// A pass for printing the PhiValues for a function.
125///
126/// This pass doesn't print whatever information the PhiValues happens to hold,
127/// but instead first uses the PhiValues to analyze all the phis in the function
128/// so the complete information is printed.
129class PhiValuesPrinterPass : public PassInfoMixin<PhiValuesPrinterPass> {
130 raw_ostream &OS;
131
132public:
133 explicit PhiValuesPrinterPass(raw_ostream &OS) : OS(OS) {}
135};
136
137/// Wrapper pass for the legacy pass manager
139 std::unique_ptr<PhiValues> Result;
140
141public:
142 static char ID;
144
145 PhiValues &getResult() { return *Result; }
146 const PhiValues &getResult() const { return *Result; }
147
148 bool runOnFunction(Function &F) override;
149 void releaseMemory() override;
150 void getAnalysisUsage(AnalysisUsage &AU) const override;
151};
152
153} // namespace llvm
154
155#endif
This file defines the DenseMap class.
This file defines the DenseSet and SmallDenseSet classes.
#define F(x, y, z)
Definition: MD5.cpp:55
This header defines various interfaces for pass management in LLVM.
This file implements a set that has insertion order iteration characteristics.
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:661
A container for analyses that lazily runs them and caches their results.
Definition: PassManager.h:620
Represent the analysis usage information of a pass.
Value handle with callbacks on RAUW and destruction.
Definition: ValueHandle.h:383
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:308
The analysis pass which yields a PhiValues.
Definition: PhiValues.h:115
PhiValues run(Function &F, FunctionAnalysisManager &)
Definition: PhiValues.cpp:191
A pass for printing the PhiValues for a function.
Definition: PhiValues.h:129
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: PhiValues.cpp:195
PhiValuesPrinterPass(raw_ostream &OS)
Definition: PhiValues.h:133
Wrapper pass for the legacy pass manager.
Definition: PhiValues.h:138
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
Definition: PhiValues.cpp:215
bool runOnFunction(Function &F) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
Definition: PhiValues.cpp:210
PhiValues & getResult()
Definition: PhiValues.h:145
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: PhiValues.cpp:219
const PhiValues & getResult() const
Definition: PhiValues.h:146
Class for calculating and caching the underlying values of phis in a function.
Definition: PhiValues.h:40
void invalidateValue(const Value *V)
Notify PhiValues that the cached information using V is no longer valid.
Definition: PhiValues.cpp:137
const ValueSet & getValuesForPhi(const PHINode *PN)
Get the underlying values of a phi.
Definition: PhiValues.cpp:125
SmallSetVector< Value *, 4 > ValueSet
Definition: PhiValues.h:42
bool invalidate(Function &, const PreservedAnalyses &, FunctionAnalysisManager::Invalidator &)
Handle invalidation events in the new pass manager.
Definition: PhiValues.cpp:26
void releaseMemory()
Free the memory used by this class.
Definition: PhiValues.cpp:157
void print(raw_ostream &OS) const
Print out the values currently in the cache.
Definition: PhiValues.cpp:163
PhiValues(const Function &F)
Construct an empty PhiValues.
Definition: PhiValues.h:45
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:152
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:301
LLVM Value Representation.
Definition: Value.h:74
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
A CRTP mix-in that provides informational APIs needed for analysis passes.
Definition: PassManager.h:394
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:69
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:371